This invention relates generally to apparatus and method for transferring specific radio configuration data from one radio microcomputer to another and more particularly to radiotelephone system subscriber radio transceivers having the capability for effecting a secure transfer of the radio-specific configuration parameters stored in transceiver microcomputer memory from one memory to another, replacement, memory.
Microprocessor controlled radio transceivers offer substantial flexibility in their operational characteristics such as the selection of radio channels for transmission and reception, the determination of transceiver individual or group identification, or the provision of specific options to satisfy a particular user. Generally, the programming of such characteristics or configurations are accomplished via a memory device coupled to the data bus of the microprocessor. In some applications, the memory device is a ROM which may be programmed once and coupled to the microprocessor bus. Alternatively, reprogrammable memory devices (EEPROMs) may be programmed many times to add user functions or to modify individual or group identity. Modification of a unit's identification has been shown in U.S. Pat. No. 4,593,155 while modification of other parameters has been shown in U.S. patent application Ser. No. 815,472 filed on behalf of Snowden et al. on Dec. 31, 1985. Remote reconfiguration of a unit has been shown in U.S. patent application Ser. No. 770,037 filed on behalf of Comroe et al. on Aug. 27, 1985.
In those applications where the programming of features or identification in the microprocessor system activates features for which the user pays a premium or provides service billing information, the service provider desires to protect the programming from tampering. The cellular radiotelephone system offers a good example of both such feature and identification programming. The telephone number of a mobile or portable cellular radiotelephone and operational characteristics are mapped into an electronic mobile identification number. The storage medium is then affixed to the radiotelephone unit in such a manner that attempted removal or tampering causes destruction of the medium. Greater detail is provided in Electronic Industries Association Interim Standard IS-3-B, Section 2.3, July 1984.
Unfortunately, enterprising individuals have been able to alter the memory storage devices and fraudulently obtain radiotelephone service. Equipment manufacturers have attempted to further combat this alteration by encoding the stored information in a manner that makes alteration very difficult. (See Cellular Fraud Preventable", Cellular Business, June 1987, pg. 34).
This solution spawns a different problem. When a radiotelephone unit is brought to a repair facility for repair, the radiotelephone user naturally wishes his unit returned as quickly as possible. The miniaturization of the radiotelephone unit has compressed many functions into field-replaceable modules so that it is expeditious to replace a module and return the user to service quickly and attempt troubleshooting and repair of a defective component at a later time. If the replaced module contains the storage medium with the identification number and the number is encoded with a security algorithm, replacement of the module will not return the unit to operation. Broadcast of the encoding algorithm to many service centers defeats the purpose of the security encoding. Thus, there is a need for the equipment and process which prevents tampering and alteration of unit identification while allowing easy and inexpensive unit repair.